I got one recently. It sticks to the wall with suction.

Pros:

• Fun
• If you’re trying to line up multiple points on a long line, it works reasonably well.
• Lasers

Cons

• In my level, the entire level needs to be moved to get a level laser line. Other levels move the laser independently.
• Bumps on the wall truncate the beam
• Feels like measuring and a long straight edge could accomplish the same thing.

I’m not sure I’d buy it again, but I use it when it’s helpful.